This article is about the current New York City Subway line under Sixth Avenue through Midtown Manhattan. For the former elevated line through Midtown Manhattan, see IRT Sixth Avenue Line. For the current New York City Subway line under Sixth Avenue through Lower Manhattan, see IND Eighth Avenue Line. For the current PATH tubes under Sixth Avenue through Lower Manhattan, see Uptown Hudson Tubes.

The Sixth Avenue Line, constructed in stages during the 1930s, was the last trunk line built by the Independent Subway System (IND) before it was incorporated into the modern-day New York City Subway. It was more difficult to build than other subway trunk lines in New York City because construction had to proceed around, over, and under existing tunnels and elevated structures. The Sixth Avenue Line replaced the Interborough Rapid Transit Company (IRT)'s Sixth Avenue elevated, which closed in 1939. The first section of the line opened in 1936 from West Fourth Street to East Broadway with service provided by Eighth Avenue Line trains. This section was initially referred to as the Houston-Essex Street Route. The Sixth Avenue subway was completed in 1940, providing service north of West Fourth Street, connecting to the Queens Boulevard Line and the Eighth Avenue Line.

Initially, the Sixth Avenue Line carried only local service, since there were no express tracks between 34th Street and West 4th Street. In 1967 and 1968, the Chrystie Street Connection was completed, connecting the line with former BMT lines in Brooklyn via the Manhattan Bridge and with the BMT Jamaica Line over the Williamsburg Bridge. Two new stations at 57th Street and Grand Street, as well as a pair of express tracks between 34th and West 4th Streets, were built to provide the necessary capacity for the new service to Brooklyn.

There are branches on both ends of the line. On the south end, the express tracks used by the B and ​D trains diverge to Grand Street and the Manhattan Bridge. The local tracks continue through the Rutgers Street Tunnel and to York Street in Brooklyn (used by the F train) or via the Chrystie Street Connection and the Williamsburg Bridge to the BMT Jamaica Line in Brooklyn (used by the M train). On the north end, north of 47th–50th Streets–Rockefeller Center, the express tracks diverge to Seventh Avenue–53rd Street and the IND Eighth Avenue Line, while a spur used by the F and ​M trains continues under Sixth Avenue to 57th Street and the 63rd Street Lines; the local tracks, used by the M train, merge with the IND Queens Boulevard Line and continue to Queens.

Extent and service

The following services currently use part or all of the Sixth Avenue Line,[2] whose services' bullets are colored orange:

The majority of the Sixth Avenue Line has four tracks, two local and two express. At each end, these pairs of tracks split, giving the line two north and two south ends. One of the north ends is at 57th Street, where two tracks lead south under Sixth Avenue from the IND 63rd Street Line (used by the F local train at all times). The other is just south of 59th Street–Columbus Circle, where a two-track line splits from the IND Eighth Avenue Line at a flying junction (with connections to the local and express tracks), immediately turns east under 53rd Street, and crosses the IND Queens Boulevard Line, which parallels it just to the north. At Seventh Avenue, the southbound track is above the northbound track (the same is true on the Queens Boulevard Line, though north is the opposite direction from the Sixth Avenue Line). These tracks are used by the B and D express trains.[3]

The express tracks from Columbus Circle then turn south to go under Sixth Avenue, merging with the branch from 57th Street and the local tracks' split from the IND Queens Boulevard Line (used by the M local train). The branch from 57th Street merges into both the local and express track pairs; there are no direct track connections between the local and express tracks. South of this point, the Sixth Avenue Line consists of four tracks from west to east: the southbound express track, the southbound local track, the northbound express track, and the northbound local track. After passing through 47th–50th Streets–Rockefeller Center, the two southbound tracks cross each other; the tracks from Columbus Circle become the two center express tracks, and the tracks from the Queens Boulevard Line are the two outside local tracks.[3]

South of 42nd Street–Bryant Park is a large interlocking with six crossovers and switches. The original express tracks ended just to the south at 34th Street–Herald Square and some services switched to the local tracks at the interlocking.[3] This was done because the PATH's Uptown Hudson Tubes already existed under Sixth Avenue south of 33rd Street, and so the Sixth Avenue Line local tracks were built on each side of PATH. The section between West Fourth Street–Washington Square and 34th Street–Herald Square, the only express section of this line, was originally built as a two track subway with the provision to expand to four tracks later.[4] The express tracks were added in the 1960s during the Chrystie Street Connection projects.[5] As a result, they are placed under the local tracks and PATH using the deep-bore tunneling method.[3][5]

At West Fourth Street–Washington Square, the express tracks return to the same level as the local tracks. A flying junction just to the south connects the local tracks of the Sixth and Eighth Avenue Lines. The Sixth Avenue Line then turns east under Houston Street. After Broadway–Lafayette Street, the express tracks turn south and use the Chrystie Street Connection to Grand Street before crossing the north side of the Manhattan Bridge into Brooklyn. The express tracks used to continue on to the express tracks at Second Avenue before the tracks were rerouted to the Chrystie Street Connection. The local tracks split at this point. One pair continues east to Second Avenue (used by the F train) while the other pair merges with the BMT Nassau Street Line at Essex Street (used by the M train).[3]

York Street ventilation tower for Rutgers Street tunnel

Just before approaching Second Avenue, the local tracks split into four tracks again. The two center tracks, which are not used in revenue service, dead-end just east of the Second Avenue station. They were built as part of the IND's proposed expansion in the 1930s, and would have merged with the never-built IND Worth Street Line and then entered Brooklyn. The line would have run to Utica Avenue in Brooklyn if it were completed.[6][7]:11 Other provisions for unbuilt lines exist at the mezzanine levels of the Second Avenue and East Broadway stations, where unfinished open spaces indicate where stations for the Second Avenue Subway and IND Worth Street Line, respectively, would have been built.[7]:13[8]

In 1924, the IND submitted its list of proposed subway routes to the New York City Board of Transportation (NYCBOT), which approved the program. The IND's program consisted of two lines underneath Sixth Avenue in Manhattan. The first line would be a 0.74-mile-long (1.19 km) section in Lower Manhattan between Lispenard Street to the south and Eighth Street to the north, comprising part of the present-day Eighth Avenue Line. The second line would be a 2.47-mile-long (3.98 km) section running between Carmine Street to the south and 53rd Street to the north, comprising much of the present-day Sixth Avenue Line. South of Carmine Street, the Sixth Avenue Line would curve east under Houston Street, then south under Essex Street and Rutgers Street before continuing south into Brooklyn.[13]

Work on the core section of the IND Sixth Avenue Line, located between Fourth and 53rd Streets, was not to begin for several years. The section of Sixth Avenue from Ninth to 33rd Streets was already occupied by the Hudson & Manhattan Railroad (H&M)'s Uptown Hudson Tubes. At first, the city intended to take over the portion of the Uptown Tubes under Sixth Avenue for IND use, then build a pair of new tubes for the H&M directly underneath it. The IND had committed to building the Sixth Avenue line, and the H&M's 33rd Street terminal was located both above and below preexisting railroad tunnels, hence the IND's plan to convert part of the H&M tubes.[14] However, the H&M objected, and so negotiations between the city and IND and the H&M continued for several years.[15]

The IND and H&M finally came to an agreement in 1930. The city had decided to build the IND Sixth Avenue Line's local tracks around the pre-existing H&M tubes, and add express tracks for the IND underneath the H&M tubes at a later date.[11] However, the city still planned to eventually take over the H&M tracks, convert them to express tracks for the IND line, then build a lower level for the H&M.[16]

The IND started advertising bids for the section of the Sixth Avenue Line between 43rd and 53rd Streets in April 1931.[17] However, that May, construction was postponed because of fears that it would disrupt the Catskill Aqueduct, one of the New York City water supply system's crucial water mains to Brooklyn and Queens.[18] The NYCBOT wanted to start work on the section between 33rd and 39th Streets first so that the engineering issues with the H&M tubes and water main could be resolved.[19] In January 1932, the city announced an agreement with the New York City Water Supply Board. The IND wanted to start construction on the Sixth Avenue line by June so that some of the projected train traffic on the Eighth Avenue line, which was slated to open that year, could be rerouted through Sixth Avenue instead.[20] In 1933, the New York City Board of Estimate requested a $25.5 million federal loan for the construction of the Sixth Avenue line.[21]

Opening of southern section

The first portion of the line to be constructed was then known as the Houston–Essex Street Line, which ran under Houston, Essex, and Rutgers Streets. The contract for the line was awarded to Corson Construction in January 1929, at which time the city began evicting 10,000 residents within the line's route.[22] Construction of this section officially started in May 1929.[23] The contract for the Rutgers Street Tunnel, connecting Manhattan and Brooklyn, was awarded in May 1930.[24] In May 1933, the city started widening Essex and Rutgers Streets to accommodate the future subway line underneath.[25]

The Houston and Essex Street Line began operations at noon on January 1, 1936 with two local tracks from a junction with the Eighth Avenue Line south of West Fourth Street–Washington Square east under Houston Street and south under Essex Street to a temporary terminal at East Broadway. E trains, which ran from Jackson Heights, Queens to Hudson Terminal, were shifted to the new line to East Broadway.[26] Two express tracks were built on the portion under Houston Street until Essex Street-Avenue A; the tracks were intended to travel under the East River and connect with the never-built IND Worth Street Line in Williamsburg, Brooklyn.[8]

Just after midnight on April 9, 1936, trains began running under the East River via the Rutgers Street Tunnel, which connected the Houston-Essex Street Line with the north end of the Culver Line at a junction with the Eighth Avenue Line north of Jay Street–Borough Hall. E trains were sent through the connection to Church Avenue. Simultaneously, the Fulton Street Line was opened to Rockaway Avenue and the A and C trains, which had used Smith Street, were rerouted to Fulton Street.[27][28]

Construction and opening of Midtown section

In April 1935, engineers started planning in earnest for the Midtown section of the Sixth Avenue Line.[29] The first contract for the construction of this section was awarded to Rosoff-Brader Construction in October 1935.[30] On March 23, 1936, Mayor Fiorello H. La Guardia broke ground for the Sixth Avenue subway at Bryant Park.[4]

53rd Street powerhouse

The construction of the Sixth Avenue line was very difficult because of the various utilities and tunnels above, below, and beside the line. At the time, it was considered the costliest subway line in the city.[31] Builders had to use very small charges of dynamite so that they would not disrupt the H&M tunnels alongside the route, the street and elevated line above it, and the water main below it.[32] The Sixth Avenue Elevated had to be underpinned during construction, adding another $4 to $5 million to construction costs. The Catskill Aqueduct was located around 200 feet (61 m) below the avenue's surface, and workers on the new subway had to be careful to not cause any cracks in the aqueduct.[4][31] As part of the construction of the IND line, the H&M's 14th Street and 23rd Street stations had to be rebuilt to provide space for the IND's 14th Street and 23rd Street stations, which would be located at a similar elevation. The 19th Street station was not affected because the IND tracks were located below the H&M tracks at that point.[4] However, the 33rd Street station had to be relocated to the south of its existing location, above the new IND line. The IND platforms were to be located at the same elevation as the present H&M station, and there was no room to build a new subway station either above or below the level of the existing H&M station.[31]

The H&M's 33rd Street terminal closed on December 26, 1937 and service on the H&M was cut back to 28th Street to allow for construction on the subway to take place.[33] The 33rd Street terminal was moved south to 32nd Street and reopened on September 24, 1939. The city had to pay $800,000 to build the new 33rd Street station and reimbursed H&M another $300,000 to the H&M for the loss of revenue.[34] The 28th Street station was closed at this time because the southern entrances to the 33rd Street terminal were located only two blocks away, rendering the 28th Street stop unnecessary. It was demolished to make room for the IND tracks below.[35] The IRT's Sixth Avenue elevated ultimately closed in December 1938, just before the Sixth Avenue subway was completed.[36]

In addition to threading around the H&M tunnel, the line had to pass over the BMT Canarsie Line along 14th Street, over the tunnels leading to Penn Station, under the four-track BMT Broadway Line at Herald Square, over the IRT Flushing Line at 41st Street, and under the 42nd Street Shuttle. Even though the line had to pass around multiple transit lines, the grades were kept to a minimum.[4] Bellmouth tunnels north of 47th–50th Streets were built to allow for a future extension under Central Park and along Morningside Avenue to 145th Street. This extension was part of the Board of Transportation's long-range program, and was estimated to cost $34.914 million as of August 1940. Construction was expected to start some time after 1946.[37]

Sixth Avenue Subway Will Be Opened to the Public at 12–01 A.M. Sunday, Dec 15, 1940

IND services immediately after the main part of the line opened

On December 15, 1940, local subway service began on Sixth Avenue from the West Fourth Street subway station to the 47th–50th Streets station with track connections to the IND 53rd Street Line. The construction of the Sixth Avenue Line cost $59.5 million.[4] The opening of the Sixth Avenue Line relieved train traffic on the Eighth Avenue Line, which was used by all services except for the G Brooklyn–Queens Crosstown service. The additional capacity allowed for the reintroduction of the AA for off-peak service between 168th Street and Hudson Terminal via the Eighth Avenue Line, and the creation of the rush-hour BB between 168th Street and 34th Street-Herald Square via Sixth Avenue. In addition, the D train, which ran between Norwood–205th Street and Hudson Terminal via Sixth Avenue, was introduced to provide service between Sixth Avenue and the Concourse Line. The F train, running between Parsons Boulevard and Church Avenue via Sixth Avenue, was created to provide express service between Sixth Avenue and Queens. Finally, the E train was cut back from Church Avenue to Broadway–Lafayette Street, running to Queens via the Eighth Avenue Line.[38][39][40]

Sixth Avenue express tracks and the Chrystie Street Connection

On April 19, 1961, ground was broken for a $22 million project to build two express tracks between the West Fourth Street and 34th Street–Herald Square stations.[5] The express tracks were built 80 feet (24 m) feet beneath the surface. The construction was done in two portions. The first section was between West 9th and 19th Streets, and the second section was between West 19th and 31st Streets.[41] The express tracks were part of an $80 million subway improvement program that began with the reconstruction of the DeKalb Avenue station in Brooklyn. The second phase of construction, was the Chrystie Street Connection, which would connect the BMT lines coming over the Manhattan Bridge and the Williamsburg Bridge with the IND Houston Street Line.[42][43] There was also to be a new two-track spur line between West 52nd and 58th Streets with a terminal at 57th Street.[44] The two projects would allow 45 additional trains per hour, carrying a combined 90,000 passengers, to enter Manhattan during rush hours.[42][43]

However, the section between 9th and 19th Streets soon experienced various delays: although it had started in April 1961,[5] work was halted by a water main break in 1962,[45] and by July 1963, the work was only 20 percent complete.[46] Construction on the section between West 19th and 31st Streets was further along: it had started in the middle of 1961, and was 60 percent complete in July 1963.[46] The first section was 88 percent complete on June 30, 1965, and the second section was 99 percent complete on that date. Between West 55th and 58th Street, a third of the structural work was done by this date.[41] No stations were constructed along the new express tracks, but provisions were incorporated into the design of the tunnel to permit the addition of future lower level stations at 14th Street and 23rd Street without disturbances to train operation.[46]

On November 26, 1967, the first part of the Chrystie Street Connection opened and Sixth Avenue Line express tracks opened from 34th Street–Herald Square to West Fourth Street–Washington Square. With the opening of the connection to the Manhattan Bridge, BB service was renamed B and it was extended via the new express tracks and the connection to the BMT West End Line in Brooklyn. D service was routed via the connection and onto the BMT Brighton Line instead of via the Culver Line. It only ran express during rush hours. F service was extended from Broadway–Lafayette Street during rush hours, and from 34th Street during other times to Coney Island via the Culver Line.[7]:216—217[47][48] On July 1, 1968, the 57th Street station and the portion of the Chrystie Street Connection connecting the line with the Williamsburg Bridge opened.[49][50] Service on the KK was inaugurated, running from 57th Street to 168th Street on the BMT Jamaica Line. B service was extended during non-rush hours from West Fourth Street to 57th Street. D trains began running express via the Sixth Avenue Line at all times.[49]

Later improvements

The tracks at 57th Street were originally built for a proposed extension under Central Park to Harlem.[4] The stub-end tracks were eventually connected to the IND 63rd Street Line when the latter opened in October 1989. The 63rd Street line only extended to the 21st Street–Queensbridge station in Queens, and did not connect to any other lines in that borough. The Q train served the 63rd Street extension on weekdays and the B train stopped there on the weekends; both services used the Sixth Avenue Line.[51] The Q train, a part-time express within Brooklyn via the BMT Brighton Line, ran along the Sixth Avenue Line between 1988 and 2001, when the Manhattan Bridge south tracks were closed for reconstruction.[52][53]

Planning for the 63rd Street Line's $645 million connection from the 21st Street–Queensbridge station to the IND Queens Boulevard Line in Queens began in December 1990, and construction began on September 22, 1994.[54][55][56] The Connector came into regular use on December 16, 2001. A new Sixth Avenue local service, the V, was introduced operating local via Sixth Avenue and terminating in the center tracks of the Sixth Avenue Line's Second Avenue station. The V ran local on the Queens Boulevard Line, and it only operated during weekdays. At this time, the F, which ran express along the Queens Boulevard Line, was rerouted to operate via the 57th Street station and the 63rd Street line north of the 47th–50th Streets–Rockefeller Center station, rather than via the 53rd Street tunnel. Both the 63rd Street and the 53rd Street lines merge into the Queens Boulevard Line in Queens.[57][58] On June 28, 2010, the V was replaced by the M, which began using the Chrystie Street Connection to the Williamsburg Bridge. Regular M trains make all former V stops except for Second Avenue.[59][60][61]

In 2004, full Manhattan Bridge service was restored. This resulted in full B and D express service being restored from 34th Street–Herald Square to the Manhattan Bridge, where the services continued to Brooklyn. However, the terminals of the B and D were reversed from prior to the Manhattan Bridge service suspensions. B service operates weekdays only via the Brighton Line express tracks to Brighton Beach, replacing the <Q> express on the Brighton Line. D service operates 24/7 along the West End Line because residents of Bensonhurst, a neighborhood located near the West End Line, wanted full-time direct subway service to Manhattan.[62]

The 2015–2019 Metropolitan Transportation Authority Capital Plan called for the Sixth Avenue Line's 23rd Street and 57th Street stations, along with 31 others, to undergo a complete overhaul as part of the Enhanced Station Initiative. Updates would include cellular service, Wi-Fi, USB charging stations, interactive service advisories and maps, improved signage, and improved station lighting.[63][64] The renovations at both stations were supposed to last from July to December 2018. The renovations were conducted under a $124.9 million contract that also included the renovation of the 28th Street station on the IRT Lexington Avenue Line.[65] 23rd Street reopened ahead of schedule on November 29, 2018,[66] while 57th Street reopened on December 19, 2018.[67]

^ a b c dLevey, Stanley (April 19, 1961). "Construction of New IND Tunnel For 6th Ave. Line Begins Today; Express Tracks Deep Under Street to Run From 4th to 34th St. – 1964 Finish Set for $22,000,000 Job". The New York Times. ISSN0362-4331. Retrieved April 28, 2018.

^"100 Miles of Subway in New City Project; 52 of them in Queens" (PDF). The New York Times. September 16, 1929. p. 1. ISSN0362-4331. Retrieved June 11, 2014.

^ abcRaskin, Joseph B. (2013). The Routes Not Taken: A Trip Through New York City's Unbuilt Subway System. New York, New York: Fordham University Press. ISBN 978-0-82325-369-2.

^"Two Subway Routes Adopted by City". The New York Times. August 4, 1923. p. 9. ISSN0362-4331. Retrieved August 1, 2019.

^"Plans Now Ready to Start Subways". The New York Times. March 12, 1924. p. 1. ISSN0362-4331. Retrieved August 1, 2019.

^ ab"Delaney For Razing Elevated Line Now; Work in 6th Av. Could Begin in Six Months if Condemnation Started at Once, He Says. Sees Cut In Subway Cost Eliminating Need for Underpinning Would Save $4,000,000 and Speed Construction, He Holds". The New York Times. January 11, 1930. ISSN0362-4331. Retrieved April 27, 2018.

^"Ends Move To Scrap 6th Avenue Elevated; Transit Commission Explains No Interest Has Been Shown in Demolition Since January". The New York Times. September 17, 1931. ISSN0362-4331. Retrieved April 28, 2018.

^"New Subway Routes in Hylan Program to Cost $186,046,000 – Board of Transportation Adopts 22.90 Miles of Additional Lines – Total Now $345,629,000 – But the Entire System Planned by Mayor Involves $700,000,000 – Description of Routes – Heaviest Expenditures Will Be Made on Tunnels – No Allowance for Equipment – New Subway Routes to Cost $186,046,000". The New York Times. March 21, 1925. ISSN0362-4331. Retrieved April 8, 2018.

^"6th Av. Subway Plan Hinges On Tubes' Use; City Must Reach Agreement With Hudson & Manhattan to Carry Out Project". The New York Times. November 20, 1924. ISSN0362-4331. Retrieved April 26, 2018.

^"Final Contracts To Finish Subway Awarded By City; Include $20,000,000 for Cars, Equipment and Substations for Manhattan Line. Operation Set For 1931 Board of Transportation Moves to Rid Sixth Avenue of Trolley Tracks. Seeks To Buy Franchise Line Willing to Exchange It for Bus Permit—Negotiations Pushed to Extend Tube". The New York Times. August 1, 1929. ISSN0362-4331. Retrieved April 26, 2018.

^"6th Av. Tube Work to be Begun Oct. 1". The New York Times. August 8, 1935. p. 23. ISSN0362-4331. Retrieved October 7, 2011.

^"The Sixth Avenue Subway". The New York Times. April 21, 1931. ISSN0362-4331. Retrieved April 28, 2018.

^"6th Avenue Subway Is Put Off 18 Months; Delaney Delays Start Because of Peril to Water Main to Brooklyn and Queens. Awaits New Supply Tube Announcement Follows Conference With Dietz Over Danger of Damage From Blasting. Action Is A Surprise Bids for Work on New City Link Already Advertised—Many Obstacles to Project Arose. Work Ahead of Schedule. Many Obstacles Arose". The New York Times. May 6, 1931. ISSN0362-4331. Retrieved April 28, 2018.

^"Speed Plan For Link Of 6th Av. Subway; Transportation Board Engineers Want Work Started First From 33d to 39th Street". The New York Times. May 8, 1931. ISSN0362-4331. Retrieved April 28, 2018.

^"Plans Work In June on 6th Av. Subway; City to Push Section North of 29th St. to Permit Routing of Eighth Av. Line. Contracts To Be Let Soon Agreement With Water Supply Board Opens Way for Construction Held Up by Condult Hazards". The New York Times. December 1, 1931. ISSN0362-4331. Retrieved April 28, 2018.

^"$25,500,000 Loan For Transit Asked; Transportation Board Applies for Federal Funds to Finish Subway System. 22-Month Task Ahead Projects to Add 18 Miles to the City's Network Planned to Start Immediately". The New York Times. October 3, 1933. ISSN0362-4331. Retrieved April 28, 2018.

^"East Side Subway Will Evict 10,000; Work on New Line, Likely to Begin in May, Will Force Many Tenants to Move. 200 Buildings Will Fall Transportation Board Notifies Property Owners—Condemnation to Coat Over $11,000,000. Expect Work to Start in May. Residents Recall Other Days". The New York Times. February 24, 1929. ISSN0362-4331. Retrieved April 28, 2018.

^"East Side Subway Started By Mayor; He Breaks Ground for Crosstown System at Second Av. and East Houston St. Miller Hails Project Sees Area Rejuvenated by Line and City's Plan to Raze Old Tenements". The New York Times. May 2, 1929. ISSN0362-4331. Retrieved April 28, 2018.

^"$13,000,000 Contracts For Subways Let; One for $11,674,060 Is for Construction of East River Tunnel to Brooklyn". The New York Times. May 22, 1930. ISSN0362-4331. Retrieved April 28, 2018.

^"Begins Street Widening.; City Will Increase Essex and Houston From 50 to 80 Feet". The New York Times. May 8, 1933. ISSN0362-4331. Retrieved April 28, 2018.

^ abcde"LaGuardia Opens New Subway Link". The New York Times. January 2, 1936. p. 1. ISSN0362-4331. Retrieved October 7, 2011.

^"New Subway Link Opened by Mayor". The New York Times. April 9, 1936. p. 23. ISSN0362-4331. Retrieved October 7, 2011.

^"Plans To Be Drawn For 6th Av. Subway; 80 Engineers and Draftsmen to Begin Work at Once on Detailed Specifications". The New York Times. March 1, 1935. ISSN0362-4331. Retrieved April 28, 2018.

^"Subway Award Goes To Rosoff Company; Sixth Av. Contract Is Let Under Specified Use of Excavated Rock Despite Lower Bid". The New York Times. October 31, 1935. ISSN0362-4331. Retrieved April 28, 2018.

^ abcHarrington, John W. (May 5, 1935). "City Plans Its Costliest Subway; In a Short Two Miles Under Sixth Avenue the Engineers Will Encounter Many Intricate Problems". The New York Times. ISSN0362-4331. Retrieved April 28, 2018.

^"Hudson Tube Terminus At 33d St. Closes Today". The New York Times. December 26, 1937. ISSN0362-4331. Retrieved April 26, 2018.

^"Hudson Tube Opens Terminal Today – Remodeled 33d St. Station Cost City $800,000 as Part of 6th Ave. Subway Expense – Closed for Two Years – Two Train Platforms and 3 Sets of Tracks Among New Transit Equipment". The New York Times. September 24, 1939. ISSN0362-4331. Retrieved April 15, 2018.

^"Tube Terminal to Reopen – Station at 33d St. and 6th Ave. to Renew Service Sept. 24". The New York Times. September 12, 1939. ISSN0362-4331. Retrieved April 15, 2018.

^"Gay Crowds On Last Ride As Sixth Ave. Elevated Ends 60-Year Existence; 350 Police On Duty But the Noisy Revelers Strip Cars in Hunt for Souvenirs Suit May Delay Razing Little Threat Seen to Plan, However-Jobless Workers to Press Their Protest Makes Only One Stop Entrances Are Boarded Up Final Trains Run On Elevated Line Police Guard Structure". The New York Times. December 5, 1938. ISSN0362-4331. Retrieved April 26, 2018.

^"Transit Projects Seek $771,256,499 – Board Asks This as Capital Outlay for 6 Years, Including $154,330,244 for 1941 – Outlines Vast Program – Ambitious Plans to Make Most of Unification Face Knife of Planning Commission – $10,607,000 Engineering Cost – Wants Transfer Links". The New York Times. August 12, 1940. ISSN0362-4331. Retrieved April 15, 2018.

^"The New Subway Routes". The New York Times. December 15, 1940. ISSN0362-4331. Retrieved April 15, 2018.

^"6th Ave. Tube Adds Two New Services – Provides Express Facilities to Queens and Local Trains to Washington Heights – Subway Opens on Dec. 15 – Changes in Routings on Other Lines to Bring Faster Time and Less Congestion". The New York Times. December 5, 1940. ISSN0362-4331. Retrieved April 15, 2018.

^"New Subway to Add 2 Need Services – Opening of 6th Ave. Line to Provide Uptown Local Route and More Queens Expresses". The New York Times. December 2, 1939. ISSN0362-4331. Retrieved April 15, 2018.

^ a bAnnual Report 1964–1965. New York City Transit Authority. 1965.

^ a b"Construction of New IND Tunnel For 6th Ave. Line Begins Today; Express Tracks Deep Under Street to Run From 4th to 34th St. – 1964 Finish Set for $22,000,000 Job". The New York Times. April 19, 1961. ISSN0362-4331. Retrieved July 8, 2016.

^ a b"Ground Breaking Program For Additional Subway Tracks". New York City Transit Authority. April 19, 1961. Retrieved January 25, 2016 – via thejoekorner.com.

^"IND Contract Awarded". The New York Times. December 27, 1963. ISSN0362-4331. Retrieved September 18, 2017.

^Perlmutter, Emanuel (November 16, 1967). "Subway Changes to Speed Service: Major Alterations in Maps, Routes and Signs Will Take Effect Nov. 26" (PDF). The New York Times. ISSN0362-4331. Retrieved July 7, 2015.

^ abPerlmutter, Emanuel (November 27, 1967). "BMT-IND Changes Bewilder Many – Transit Authority Swamped With Calls From Riders as New System Starts". The New York Times. ISSN0362-4331. Retrieved August 23, 2015.

^* "Two Subway Units Open at Midnight – Links in City-Owned System in Queens and Brooklyn to Have 15 Stations" (PDF). The New York Times. August 18, 1933. ISSN0362-4331. Retrieved November 7, 2015.

"New Queens Subway Service Will Be Launched Tonight; Tunnel From Manhattan Open to Jackson Heights; Service Will Eventually Be Extended Through To Jamaica" (PDF). Long Island Daily Press. Fultonhistory.com. August 18, 1933. p. 20. Retrieved July 27, 2016.

"New Queens Tube To Open Saturday: Brooklyn-Long Island City Link of City Line Also to Be Put in Operation" (PDF). New York Evening Post. Fultonhistory.com. August 17, 1933. p. 18. Retrieved July 27, 2016.

Note that this is a list of New York City Subway lines, which are the physical infrastructure over which services operate.Lines with colors next to them are trunk lines; trunk lines determine the color of New York City Subway service bullets, except for shuttles, which are dark gray.